(USA TODAY)ATLANTA - More than 400,000 homes and businesses were without power in Georgia and the Carolinas as a fierce winter storm cut an icy swath across much of the South, bringing traffic to a standstill and stranding travelers Wednesday.

The massive storm threatened to knock out power for hundreds of thousands more across the South before turning its sights on the Northeast. More than 100 million Americans are under some form of a winter storm warning, watch, or advisory, the National Weather Service said.

More than 4,000 commercial flights were canceled Wednesday, and another 2,000 scheduled for Thursday have already been scrubbed, Flightstats.com reported. At least 11 deaths across the South were blamed on the weather.

By evening, some 410,000 customers are without power in the Southeast from the ice storm, with more likely to come, said meterologist Matt Lanza.

"The storm is on track," weather service meteorologist Bruce Terry said. "That much freezing rain and sleet can be devastating. It will mean downed trees and power lines."

Slatemeteorologist Eric Holthaus ofSlatewarned that "it's not unreasonable to expect that Atlanta - sometimes known as 'the city in a forest'- could lose a quarter of its trees in this storm."

As the storm headed north and east, ice was giving way to snow. Washington, Baltimore and Philadelphia will see 4-8 inches of snow starting Wednesday night and all day Thursday, Terry said. New York and Boston can expect 3-6 inches. But areas north and west of all those cities could see a foot or more of snow before the nasty front rolls off the coast of Maine on Friday.

Snow was falling in parts of North Carolina, triggering major traffic jams on freeways around Durham and Raleigh, and along Interstate 95 to the east.

President Obama declared a disaster in South Carolina and parts of Georgia, opening the way for federal aid.

Snow began in the Raleigh area around noon and quickly brought travel on many roads in the region to a halt. Some motorists abandoned their vehicles when roads became snarled.

Late in the day, school officials said the 9 p.m. basketball game between neighboring schools and intense rivals University of North Carolina and Duke was canceled - after saying for much of the day that it would go on as scheduled in Chapel Hill.

Duke players were unable to travel the 9 miles to the UNC campus because of conditions, theNews & Observerof Raleigh reported.

"The (ACC) policy is to try to get the game in, and if you can get your game day personnel and the teams there safely, they encourage you to play the game," UNC athletic director Bubba Cunningham told the newspaper.

Amtrak suspended some service from New York and south of Washington, D.C., in the Carolinas, Georgia and Florida because of the storm. Amtrak suspended service on the north- and southbound Crescent, southbound Silver Star and Silver Meteor, north- and southbound Palmetto, north- and southbound Auto Train, north- and southbound Carolinian and east- and westbound Piedmont.

A snowy Thursday is forecast for most of the eastern U.S., from the Carolinas to Maine, according to AccuWeather.

The heaviest snow, as much as 12-18 inches, is forecast for the Appalachian mountains and inland regions, with lesser amounts expected for coastal areas and the big cities of the mid-Atlantic and Northeast.

"While a change to rain can occur along some of the I-95 cities and most areas along the coast, this will be a major storm throughout the corridor, with enough snow to make for slippery roads and difficult travel," according to AccuWeather meteorologist Elliot Abrams.

The Federal Emergency Management Agency said it was sending 155 power generators to Georgia and 95 to Pennsylvania, which just last week saw almost 1 million people lose power in a storm. FEMA also deployed liaison officers to the state emergency operations centers in Virginia, Maryland, Pennsylvania, Georgia and South Carolina.

Gov. Nathan Deal said Wednesday afternoon that two people have died in Georgia since the storm hit Tuesday, an elderly woman who was found dead at home in Whitfield County - that death has not been confirmed as weather-related - and a man who slipped on the ice and hit his head in Butts County.

He said 190,000 people statewide are without power. SCE&G and Duke Power almost 100,000 each on Wednesday in the Carolinas.

Atlanta, paralyzed by an ice storm two weeks ago that left highways gridlocked and children in schools overnight, was better prepared this time. As ice began accumulating on Atlanta-area roads, the state Department of Transportation said its crews were working to keep them open for essential travel.

Metro Atlanta was a virtual ghost town: Most residents had stocked up on food and essentials and were heeding the repeated, urgent warning of authorities and are staying home. All area schools, non-essential government operations and most businesses are closed.

Georgia Power had hundreds of lineman working and on call. Mobile showers, dining hall and kitchen have been set up in the Mall of Georgia's parking lot - although a kitchen worker said defrosting ribs when it's frozen outside has proven difficult.

The Georgia Department of Transportation was warning of "extreme black ice," more than 7 inches of snow across northeast Georgia and up to an inch of ice accumulation north and south of the Interstate 20 corridor.

"This is a very dangerous ice storm and we strongly encourage the public to stay off the roads unless it is an extreme emergency," said state DOT Commissioner Keith Golden.

Atlanta's Hartsfield-Jackson International Airport was operating on a minimal schedule Wednesday with more than 2,000 incoming and outbound flights canceled. More than 750 scheduled Thursday flights were already canceled.

Ali Banter, 28, said driving to his job at an Atlanta Texaco station wasn't too difficult this morning - although it did take him twice the normal amount of time due to the icy roads. The weather worsened, and he said he will most likely spend the night alone at the store.

"It's snow all-around, everywhere," the Atlanta native said. "It's a little better on the road than the last storm, but it's still all icy. Luckily, we have food in stock."